Thyroid UK
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Help with T3 and T4 test interpretat

First blood test results after stopping Eltroxin 5 weeks ago. I'd appreciate any help to understand what they mean.

Free T4 - 7.8 ref range: 7.2-16.4 pmol/L

Free T3 - 4.95 ref range: 3.10-6.80 pmol/L

Thyroglobulin AB 0.4 range 0-4.0 IU/mL

Thyroid Perioxidase Ab 5.8 range 0-9 IU/ml

S Potassium 4.4 range 3.5-5.1mmol/L

S Magnesium 0.74 range 0.77-1.03mmol/L

Serum Iron 24.9 range 10.7-32.2umol/L

Ferritin 25ug/L

Vitamin B12 104 pmol/L

Range (B12) Adequate >221pmol/L

Low 148-221pmol/L

Deficiency <148pmol/L

Previous TSH a month ago was 2.02 range 0.38-5.33mIU/L

Thanks in advance to anyone who can help.

12 Replies

Jax - Do you want to give us some background information, there's nothing in your profile.

Why have you stopped your Levo?

Where's your new TSH result?

FT4 is very low.

FT3 - your body is pushing out enough for the moment but that wont last.

Antibodies tested negative for autoimmune thyroid disease.

Magnesium low, quite usual so most of us supplement.

Range for ferritin?

You can see you are B12 deficient - you need to check for signs of B12 deficiency and then post on the Pernicous Anaemia Society forum for further advice

Folate result?

Potassium and serum iron in range.


Thanks for replying SeasideSusie.

I updated my profile, sorry I'm new here. I stopped the .05mg Levo because I have NEVER had an abnormal thyroid test result in the 14 years I have been taking it yet my quality of life has become consistently worse over this time period. I'm fed up with doctors and wanted to see if I felt better being off Levo as many have said they have. My severe bone and muscle pain is gone, I'm more clear headed than I've been in years. In general I haven't felt better since 14 years ago when I had my last child. I had to request the tests and pay for them privately because no Dr would check my T3.

Natural thyroid hormone is not available in my country, not even online and I just cannot take Eltroxin anymore as I am 100% sure it is causing my unbearable symptoms.

I couldn't afford all the tests and thought as my TSH was tested just over a month ago I could concentrate on the ones the Dr refused to test. I'm still waiting on the reverse T3 result.

Serum Folate is 18.8nmol/L

Range - Deficient: <10nmol/l


Is that Eltroxin from Aspen or from Mercury Pharma?


Helvella, I have no idea. The pharmacist dispenses it in a bottle labeled by the pharmacy?


In the UK, it is legally required that they provide a Patient Information Leaflet (if requested) with every prescription product.

Might not be the same where you are - can you describe the tablets? Shape. Colour. Markings.

Not trying to twist your arm to make you tell us, but if you are comfortable to do so, that might also help.


Pity I can't post a photo? Is that possible? Tablets are small white tablet with "EL" on one side and 50 on the other


I'm going to ask at the pharmacy when I'm there again


If you've never had an abnormal thyroid test result, how come you were prescribed levothyroxine in the first place?

Your folate is fine, but you need to sort that B12 out though, you are deficient and that will cause no end of symptoms and problems. Check out the first film in this link, you don't have to watch it all to realise how important it is to treat B12 deficiency

Try and get ferritin tested, it needs to be at least 70 for thyroid hormone to work (and that's our own as well as replacement) and recommended is half way through it's range.


Ferritin range as follows:

<15 ug/l: Iron deficiency likely (sens 41%, spec 96%)

Ferritin 15-30 ug/l: Iron deficiency anemia (IDA) with or without anemia of chronic disease (ACD) may be present (sens 59%, spec 93%)

Upper limit for ferritin is 150 ug/l

My result was 25 ug/l


Jax - that is dire! You need to improve your ferritin. As mentioned, it needs to be at least 70. And you need an iron panel and full blood count to see if you have iron deficiency anaemia.

You can help raise your level by eating liver regularly, maximum 200g per week due to it's high Vit A content, and including lots of iron rich foods in your diet


Those are my thoughts exactly. I was pregnant with my 3rd child and my second was 9 months old when I was diagnosed by a physician my gynae sent me to because I was complaining of fatigue and hair loss. I'm pretty sure it had more to do with pregnancy hormones than thyroid! But I was told I could NEVER stop the meds... So I didn't.

I am supplementing the deficiencies so hope to see a steady improvement.


I wonder if you'd be well-advised to delay supplementation to remedy your deficiencies until you've discussed your results with a doctor in case you need further investigation of some of these results - like the B12? It can be difficult to disentangle B12 deficiency and iron deficiency so you really need to talk about this with someone like a GP who can order the full tests that Seaside Susie mentions.


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